Hi Jessi,
We looked at your site, tested the watermark you’re trying to apply and… it works on our sites, it doesn’t work on yours, so the problem is not with the image you use.
Next, you’re using a complex theme (WP Pro Real Estate) and a couple of plugins. We’d have to check the possible conflicts by disabling plugins one by one, and/or changing a theme (just for tests) but we didn’t want to do it on a your site without doing a backup first.
Our suggestions:
– backup your site (DB and all the files)
– try to disable plugin one by one and check if Image Watermark starts working
– if disabling plugins will not make any difference, change a theme and test the watermark again
– whether it works or not, provide the info here and give us an ftp access to your site, so we could enable debug mode and look for possible errors